1. Field of the Invention
This invention relates to an electrical switching device and, more particularly, to a circuit interrupter, such as a circuit breaker, including a baffle.
2. Background Information
Electrical switching devices include, for example, circuit switching devices and circuit interrupters, such as circuit breakers, contactors, motor starters, motor controllers and other load controllers. Circuit breakers are generally old and well known in the art. Examples of circuit breakers are disclosed in U.S. Pat. Nos. 4,887,057; 5,200,724; and 5,341,191. Such circuit breakers are generally used to protect electrical circuitry from damage due to an overcurrent condition, such as an overload fault or a relatively high level short circuit condition.
Molded case circuit breakers, for example, include a pair of separable contacts per phase; an operating mechanism designed to rapidly open and close the separable contacts; a handle disposed on the outside of the case for operating the operating mechanism manually; and a trip mechanism for tripping the operating mechanism automatically in response to an overcurrent condition.
When the circuit breaker is on, a movable contact assembly is in contact with a stationary or fixed contact assembly. The closed contact assemblies conduct a flow of current between a line terminal and a load terminal. When the circuit breaker trips or is switched off, the movable contact assembly is moved away from the fixed contact assembly, thus, interrupting the flow of current between the line and load terminals. Examples of molded case circuit breakers are disclosed in U.S. Patent Nos. 3,815,059; 4,618,751; 4,645,890; 4,698,606; 4,827,369; 4,950,853; 4,963,846; 4,973,927; 5,223,681; and 5,278,373.
Some types of circuit breakers include an electro-mechanical trip unit which interrupts current flow in two or more modes of operation. The electro-mechanical trip unit generally senses overload currents of up to about five to six times normal rated current as well as short circuit currents of greater than about ten times normal rated current. Other types of circuit breakers include an electronic trip unit for automatically interrupting the current flow.
During an overcurrent condition, the fixed and movable contact assemblies part, with the current flowing therethrough forming an arc therebetween. Some circuit breakers employ an electrical arc chute or arc stack to divide a single electrical arc formed between the separable contacts upon a fault condition into a series of smaller electrical arcs, increase the total arc voltage, and extinguish the electrical arc.
Many arc stacks for circuit breaker venting structures are designed to release arc gas products from the circuit breaker in a manner to aid in the interruption of the circuit and to vent the gases in a safe manner such as by cooling and deionizing them. The forced flow of gases through an obstacle pathway provides a restriction of gas flow and causes high chamber pressures within the circuit breaker casing.
It is known to use multiple, generally parallel, arc plates to provide a series of vertical chambers which cause changes in the direction of gaseous flow and result in turbulence and an attendant cooling of the moving gases. It is also known to provide a back-to-back louvered arc stack and baffle arrangement to facilitate a relatively free flow of gases while sufficiently cooling and deionizing the gases. However, there is room for improvement.
There is a need for a relatively low-cost, easy to manufacture baffle arrangement for an electrical switching device and, in particular, a circuit interrupter in which arcs occur.
There is also a need for such a baffle arrangement for an electrical switching device and, in particular, a circuit interrupter in which arcs occur, which is easily reconfigured in the manufacturing process to vary the flow of gases.